Australia's three Man Booker Prize-winning authors have damned government plans to relax book import restrictions, warning to do so would make the country a dumping ground for cheap American and English books and bring a swift end to a golden age of Australian literature.

Peter Carey, (Oscar and Lucinda and The True History of the Kelly Gang) Tom Keneally (Schindler's Ark) and Richard Flanagan (The Narrow Road to the Deep North) have penned an open letter to the Prime Minister warning the proposed rule changes would decimate the local publishing industry, resulting in job losses, a shift in local profits overseas and a "brutal" reduction in the range of published Australian books.

"Australia will become, as it was in the 1960s, a dumping ground for American and English books, and we will risk becoming as we once were a colony of the minds of others," they said.

Parallel imports are books which are commercially shipped in from abroad from overseas publishers. They are restricted where a local publisher has acquired Australian publishing rights to an overseas book or to an Australian writer's work.

This gives the publishers ability, it is argued, to publish without having cheaper foreign editions undercut them and so support more speculative publishing projects.

The parallel import rules do not apply to online overseas purchases from Amazon or Book Depository.

Treasurer Scott Morrison last week backed the findings of the Productivity Commission inquiry into intellectual copyright that the import restrictions be abolished to cut the sales price of books.

While the authors concede it will mean a handful of mass market titles will become cheaper, they worry that those Australian books that continue to be published will either become more expensive or publishers will take fewer risks on worthy but marginal Australian writers.

"The overall consequence will be a great decline in the variety of books available," they said.

"These rules and rights are what allowed us and so many other Australians to become writers. These rules and rights are what enabled a golden age of Australian writing to occur.

"And it is our hope that this time of great literary achievement is an early chapter in the ever growing story of Australian literature, and not – if this decision stands – the end. We cannot return to being a colony of the mind."

Between them Carey, Keneally and Flanagan have won four Man Booker Prizes, regarded internationally as one of the world's most prestigious literary award for fiction.

To see an abolition of restrictions as a positive economic reform is to "misunderstand both the commercial realities of Australian publishing and the accepted trade rules of book publishing globally", they said.

The argument that books would become cheaper ignored existing discounting which had seen the cost of an average paperback fall from $25 to $20, a 20 per cent reduction in authors' income per book.

Were the government genuine in its desire to make books cheaper, it would exempt books from its proposed GST rise of 5 per cent, and establish the grounds for fair competition by requiring all Australian book purchases of books through Amazon be subject to GST.

"We are not arguing for protectionism because the book industry is not a protected industry," they said. "We are not asking for money, or for a subsidy. We are asking for the same rules and intellectual property rights that prevail for writers and book publishing in the USA, in Britain, in Europe and in Asia to prevail in Australia. That is all."